Question Help with ばいい form.

[Treesgotowar]

Hi, i am trying to understand how to use the form and slight differences in uses.
Can ばいい be used to give advice by itself?
I see many site where they use ば いいのに, in the following example would dropping the のに have the same meaning? How does のに change meaning?

もっと 早く 寝れば いいのに

While searching how to say "I don't know how in Japanese, i found the post below. How does のか change the meaning, i understand か acts as a question marker, instead of a statement.
にほんごでなんといえばいいのかわからない

From what iv found online
のに Can mean - Although, despite. Aim or intention.
のか endorsing and questioning the preceding statement; lamenting reflections on the preceding statement
ばいい - you should; can; it'd be good if

Thanks if you can explain.

 

[Toritoribe]

As you found, ～のに means the adversative conjunction "although, despite" there. When it's put at the end of a sentence, the following part なぜそうしないの？ "why don't you/they do that?" is omitted since it's obvious from the context. Thus, ～ばいいのに often has a nuance of blame.

～ばいい can be "giving advice" by itself, so のに can't be used for the cases where it doesn't connote "why don't you do that?".
e.g.
学校には朝8時までに行けばいい。
時間はあるから、ゆっくりやればいい。
車を貸してあげるから、自由に使えばいい。

か is the particle for question, and ～かわからない means "I don't know if/when/where/who,,,~". の is optional here.
e.g.
学校には何時までに行けばいい（の）かわからない。

 

[Treesgotowar]

Thanks. Just to clarify this sentence, since you used double negative.
学校には朝8時までに行けばいい。 It would be good if you were on school at 8am. Neutral sounding. similar to ほうがいい

Assuming a student shows up late.
学校には朝8時までに行けばいいのに。Why don't you arrive at school at 8am. Slightly negative/blame tone.

 

[Toritoribe]

学校には朝8時までに行けばいい。 is not "double negative". It's just an affirmative.

The set phrase ～ばいい is made with ～ば conditional + いい, so it literally means "it is good if~". In my example sentence, 学校に（は）朝8時までに行く is a sufficient condition; "it's enough if I'm/you are/they are at school by 8 a.m.". Thus, it's closer to "can".

On the other hand, 方/ほう means "one side" in Aほうがいい, so this set phrase always connotes that A is better than "not A"/the other side. Therefore, 学校には朝8時までに行くほうがいい is closer to "should". This is the main difference between ～ばいい and ～ほうがいい.

学校には朝8時までに行けばいいのに。 indeed has a nuance of blame, but this is used when the addressee is going to go to school earlier than 8 a.m., something like "Why are you going to go to school so early, despite being enough at school by 8 a.m.?".

Also, 学校には朝8時までに行けばいい。 is the future tense or a habitual action. This cannot be used for a past event.